PURPOSE: To provide a fixing device capable of preventing the occurrence of vibration due to retained toner sticking to a temperature detector.

CONSTITUTION: The temperature detector 1 is covered with an outside coating film 5 installed separately from the detector 1. Thus, a temperature detecting part 2 is doubly covered with the outside coating film from the outside of the protective film 4. And, the offset toner OT shifted to a fixing roller 7 sticks to the film 5. High viscosity is developed in the sticking and remaining toner TT by the heat of the fixing roller 7, then, the slip between the temperature detector 1 and the fixing roller 7 is worsened, then, the vibration occurs, but the vibration is absorbed by the film 5 installed separately from the detector 1. Thus, the detector 1 is prevented from vibrating itself, and the occurrence of an abnormal noise and the disconnection of a lead wire are prevented.